Explain Kotlin compiler pin without referencing old rules

Describe the older extractors' language-version requirement directly rather than referring to the removed rules_kotlin version.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jketema

MODULE.bazel

@@ -37,7 +37,7 @@ bazel_dep(name = "zstd", version = "1.5.7.bcr.1")
 
 bazel_dep(name = "buildifier_prebuilt", version = "10.1.0", dev_dependency = True)
 
-# Keep the compiler used by rules_kotlin 2.2.2 so we can still build for Kotlin 1.8 and 1.9.
+# Pin the compiler to support the Kotlin 1.8 and 1.9 language versions required by older extractors.
 kotlin = use_extension("@rules_kotlin//src/main/starlark/core/repositories:bzlmod_setup.bzl", "rules_kotlin_extensions")
 kotlin.kotlinc_version(
     sha256 = "a623871f1cd9c938946948b70ef9170879f0758043885bbd30c32f024e511714",